association between the functional polymorphism of vascular endothelial growth factor gene and breast cancer: a meta-analysis

the vascular endothelial growth factor (vegf) gene single-nucleotide polymorphism involved in the regulation of the protein levels has been implicated in breast cancer. however, the published studies have produced contentious and controversial results. herein, we performed a meta-analysis (from january to october 2013); to further evaluate the association between +936 c/t polymorphism and the risk of breast cancer. by searching the embase, pubmed, and web of science databases, we identified a total of 12 case-control studies with 8,979 cancer patients and 9,180 healthy controls. the strength of the association was assessed using odds ratios (ors) with 95% confidence intervals (ci). we found no evidence indicating that the allelic model or the genotype models of +936 c/t polymorphism were associated with the risk of breast cancer in total population (orcc vs. tt=1.01, 95% ci=0.96-1.06, ph=1.00; orcc+ct vs. tt=1.00, 95% ci=0.96-1.05, ph=1.00; orcc vs. ct+tt=1.02, 95% ci=0.98-1.07, ph=0.94; or allele c vs. allele t=1.01, 95% ci=0.98-1.04, ph=0.99; orct vs. tt=1.01, 95% ci=0.93-1.09, ph=1.00). such lack of association with breast cancer was also observed in subgroup analyses according to ethnicity as well as in the analysis by source of controls. in conclusion, this meta-analysis suggests that the functionally important +936 c/t polymorphism may not be associated with breast cancer risk. larger well-designed studies with gene-to-gene and gene-to-environment interactions are clearly required to validate the results further.